Enabling pumped storage at an existing 60 MW powerplant in Spain

Pumped storage plays a vital role in the energy transition, providing grid stability and load balancing. Iberdrola’s strategic plan for 2024-2026 includes a major investment to increase pumped-storage capacity, in some cases with the need to overcome significant technical challenges. Existing schemes equipped with reversible units, like Valparaíso, offer a great opportunity to increase pumped-storage capacity. The two reversible 30 MW units at Valparaíso had been operating only in the turbine mode for 35 years because of instabilities during pumping. Following studies on the root cause, mitigation measures were developed which proved successful in 2021. Some fine-tuning was done in 2022 along with an upgrade of the governor and excitation systems. The authors discuss here the analyses that led to the understanding of the hydraulic instability and the measures adopted to overcome the problem.